1. Field of the Invention
The present invention relates to a motor brake, and more particularly, to an actuator used for opening and closing a valve or the like and a motor brake structure in which a rotation speed of a motor is adjusted. In particular, the present invention is directed to a motor brake structure that can be used when a Hysteresis synchronous motor is reversely rotated.
2. Description of the Related Art
Generally, in order to automatically adjust a pipeline, a valve for opening and closing the pipeline, a motor for enabling the valve to be automatically opened and closed, and an actuator being driven by the motor are used.
Specifically, when the valve is closed, a power supply is applied to energize the actuator such that the valve is closed using a rotation force of the motor. Further, when the motor is rotated in a valve close direction, a restoration force is applied to a resilient spring embedded in the actuator such that a predetermined energy is stored in the resilient spring. Additionally, when the closed valve is opened, the restoration force of the resilient spring embedded in the actuator enables the valve to be moved in its original position, that is, in a valve open direction.
On the other hand, in a course of a procedure in which the restoration force of the resilient spring enables the valve to be returned to the original position (open position), the motor is reversely rotated. Further, the rotation speed of the reversely-rotated motor is gradually sped-up by the restoration force continuously applied by the resilient spring, such that a significant fast rotation speed is resultantly accomplished.
As described above, the conventional motor brake structure has a drawback in that, if the motor is reversely rotated at a high speed, noise is generated from a connection part (for example, a gear) of a deceleration unit connected to a motor axis.
Additionally, the conventional motor brake structure has a drawback in that since a gear abrasion in the deceleration unit is excessive, its life becomes short.
Further, the conventional motor brake structure has a drawback in that in case an eccentric error of the motor axis is generated, the noise is generated from the motor itself.
Furthermore, the conventional motor brake structure has a disadvantage in that when the motor is reversely rotated at a high speed, an electromagnetic circuit of the motor is overworked.